In the context of College Football (CFB), “GEM” typically stands for “Game of the Week.” It is often used to highlight a particularly important or exciting matchup during the college football season. These games are usually anticipated due to the rankings of the teams, their rivalry status, or their implications for playoff positioning.
If you meant “GEM” in a different context or are referring to a specific analysis, ranking, or statistic within CFB 25 (which might refer to a specific ranking or poll of college football teams), please provide more details so I can give you a more precise answer.